The present invention relates to a packaging device, and in particular to a packaging device in which a filling material is introduced into a tubular casing, and to a method for controlling a packaging device.
A packaging device known from practice, in which a filling material is introduced into a tubular casing, is shown in FIG. 3. Such a packaging device can be used to produce sausages, for example.
The packaging device in FIG. 3 comprises a mostly funnel-shaped filling container or storage container for the liquid, pasty and/or granular filling material, which may, for example, be sausage meat for producing sausages. The filling material 2 is supplied to a filling unit 4. Filling unit 4, also referred to as a filler, causes filling material 2 to be ejected via a connecting pipe 5 to a valve unit 6. A filling tube 7, on which a tubular casing 8 closed at one end by means of a closure element is arranged, is connected to valve unit 6. Casing 8 is pulled in folded form from a respective supply onto at least one part of filling tube 7, and the casing end with the closure is pulled over the end of filling tube 7.
If, during operation of the packaging device, filling material 2 is transported under a predetermined pressure from storage container 1 in the direction of filling tube 7 by means of filling unit 4, then the filling material 2 is introduced into casing 8. That part of casing 8 which is filled with the filling material 2 is transported to a clipping unit 9 disposed in the direction of flow of the filling material.
Portioning is carried out in clipping unit 9 according to a predetermined filling capacity (portion size, product size) in casing 8, by the filling material being displaced in a predetermined region of casing 8 by displacement devices (not shown in FIG. 3), and by the clipping unit 9 placing two spaced-apart closure elements (not shown), such as clips, in the resultant displacement region which is in the form of an unstuffed tress, such that casing 8 is closed and the constricted part of casing 8 can be severed between the closure elements.
The individual sausage products are removed after they leave clipping unit 9, and are transported for further processing to the respective processing positions.
The packaging device further comprises a sensor unit 10, which is provided in the form of a detector for detecting impurities in filling material 2. In particular, any pieces of metal that have been undesirably introduced into filling material 2 are detected. Sensor unit 10 emits a corresponding detection signal, which is supplied to a central control unit 11 for further processing and evaluation.
When filling material 2 is being processed, and particularly during mixing and comminution of components of filling material 2, it is possible, for example, that parts of the metal tools for comminuting the components of filling material 2 can be damaged and break off. The pieces of metal which have broken off, for example parts made of light metal such as aluminum, or made of steel, are transported in the volumetric flow of filling material 2, the direction of volumetric flow in FIG. 3 being indicated by respective arrows 12 in connecting pipe 5.
If, during operation of the packaging device, filling material 2 is contaminated by such metal parts, then these metal parts may end up in the finished product (for example in a sausage), which means that the product may be hazardous for the final consumer eating the product. Such metal parts are likewise hazardous in view of the fact that the product packaged in portions in casing 8, for example, is further processed in another processing operation. In that case, apparatus and machinery provided for further processing may be damaged.
The pre-processed filling material 2 stored in container 1 is fed past the sensor unit 10 into the connecting pipe 5 under a pressure produced by filling unit 4, such that a metal part can be detected by means of the relevant known measurement methods.
If a metallic impurity in filling material 2 is detected by sensor unit 10, control unit 11 emits a corresponding alarm for the operator of the packaging device and induces shut-down of filling unit 4, so that no further filling material 2 is transported in an uncontrolled manner in the direction of valve unit 6 and filling tube 7, and hence to prevent the impurity from entering the finished product.
After a metallic impurity has been detected in filling material 2, it is necessary for measures to be carried out manually by an operator. After detection of the metal impurity by sensor unit 10 and shut-down of the filling unit 4 by operating personnel, or automatically, valve unit 6 may be switched such that any filling material 2 transported to valve unit 6 is not fed to filling tube 7 but to a discharge pipe 13 and that filling unit 4 is manually operated for a predetermined duration, and that the part of filling material 2 which contains the metal impurity is ejected via discharge pipe 13 into an appropriate container 14. The amount of filling material 2 to be ejected, i.e. the amount of filling material 2 that is not fed to filling tube 7 and hence for processing into the final product, but instead is discharged into container 14, depends on the stuffing speed resulting from the volumetric flow generated by filling unit 4. In general, a relatively large amount of filling material 2 is ejected, in order to be certain that the metal impurity is ejected.
The filling material 2 thought to contain the metallic impurity is thus ejected in a time-dependent manner according to an adjustable time associated with the predefined volumetric flow rate of filling unit 4, on the one hand, or ejection can be carried out in such a way that the ejected amount corresponds to a number of portions set on filling unit 4 (pre-adjusted amount of product).
It is also possible that direct ejection is not carried out after a metallic impurity is detected by sensor unit 10, but that connecting pipe 5 and valve unit 6 are manually cleaned instead. To do this, the device must be partially disassembled manually and re-assembled. After operation of the entire portioning and packaging device is temporarily discontinued, it is also necessary to put the device back into operation.
However, such handling is very laborious and time-consuming and leads to the undesirable and protracted stoppage of the device. Manual intervention is also required, wherein disassembly and re-assembly of the device or at least parts thereof can be dangerous for the operating personnel.
Ejecting part of filling material 2 after detection of a metallic impurity means increased loss of filling material, since a larger amount of filling material must be ejected to ensure that the contaminated filling material is definitely ejected. Hence, in addition to the extended period that operation of the device is discontinued, substantial amounts of filling material 2 are also lost.